1. Field of the Invention
The present invention relates to a longitudinally stretchable slide fastener for use on various stretchable articles such as sportswear, women's undergarments such as corsets, and the like.
2. Description of the Prior Art
Japanese Patent Publication No. 26-2382 and Japanese Utility Model Publication No. 49-43451, for example, disclose conventional stretchable slide fasteners. These known stretchable slide fasteners have stringer tapes which are stretchable warp-wise, and rows of coupling elements mounted on longitudinal edges of the stringer tapes, the rows of coupling elements being unstretchable longitudinally thereof.
Heretofore, the rows of coupling elements on the stretchable stringer tapes have been made unstretchable based on the long-believed design consideration that if stretched longitudinally, they would be split open or forced out of mutual meshing engagement. There have been no slide fasteners available so far with longitudinally stretchable rows of coupling elements.
Sportswear such as skiwear and skatewear, and women's supporting undergarments such as corsets are made mainly of stretchable fabric. Slide fasteners mounted on those stretchable garments have longitudinally unstretchable rows of coupling elements, as described above. Therefore, when the wearer of such a stretchable sportswear or undergarment does bending and stretching exercises, the portion of the wear where the slide fastener is mounted is felt as a stiff area by the wearer since it is not stretched, making the wearer feel uneasy, and also appears unsightly in comparison with the other stretched area.